There are many techniques for cleaning and sterilizing contact lenses. Contact lenses continue to be fragile and collect surface contaminants that diminish the visual capacity and useful nature of the contact lenses. Statistics show that the majority of contact lens wearers do not comply with proper cleaning and handling of contact lenses. This new method of cleaning facilitates the cleaning and disinfecting process and improves the visual clarity of the lenses for the wearer, for the recommended life of the contact lenses, in a manner that is simple, economical and quick.
Some wearers of contact lenses bypass the various cleaning processes by purchasing new lenses that are worn a few days and then disposed. This system is good for contact lens manufacturers but wasteful and expensive for the wearer.
Other wearers scrub their lenses with their fingers or use non-scrub cleaners and enzymatic drops or enzymatic soaking tablets to try to clean their contact lenses. These chemicals are costly, can be difficult to remove from the surface of the lenses and irritating to the eyes of the wearer. They can contribute to allergic reactions and eye infections. Some of the enzymatic cleaners are made from porcine pancreatic enzymes, which are against dietary laws for some wearers. Often during the cleaning process, the wearers can have the misfortune of tearing their lenses because of excess handling. Dissatisfaction with these processes of cleaning contact lenses has helped to fuel the disposable line of lenses. Surface contaminants on contact lenses can be from external sources like dirty fingers, air borne particles or from eye discharge that can consist of protein deposits or lipid and mucoid products produced by tears. Bacteria and fungal deposits have been found on contact lenses. In the lab, scientists have been unable to reproduce fungal growth on contact lenses. In April of 2006, there was a fungal outbreak among contact lens wearers, and in November 2006, there was a bacterial outbreak in some lens cleaners that had to be recalled. This method of cleaning, because of its simplicity and effectiveness can help contact lens wearers remove unhealthy contaminants on the surface of the contact lenses. This consequently, improves the clarity of the contact lenses for the recommended life of the particular type of contact lenses, and also protects the vision of the wearers.
The use of ultrasonic waves and other cleaning techniques for contact lenses has been described in the following relevant patents.
U.S. Pat. No. 3,720,402 Cummins, describes cleaning contact lenses in a “foraminous” container within a beaker filled with saline that heats and uses ultrasonic and timing means. The process of cleaning in this manner takes two hours.
U.S. Pat. No. 3,851,861 Cummins, describes an ultrasonic cleaning device that switches off above 75 degrees centigrade, to prevent damage to the lens and the heat shortens the cleaning cycle to 15-30 minutes.
U.S. Pat. No. 3,973,3760 Browning et al, uses a membranous contact lens capsule mounting to a receptacle in contact with a tuner or to a transducer element with ultrasonic means and has a 2-minute ultrasonic cycle followed with a 20-minute disinfecting cycle.
U.S. Pat. No. 4,382,824 Halleck cleans using a combination of ultrasonic waves with a heated bath.
U.S. Pat. No. 4,607,652 Yung, describes a small battery powered ultrasonic device portable and with a removable contact lens case that fits into a cavity contained within the device that operates at a frequency of 20-40 kHz. According to the inventor, the resonance of the ultrasonic apparatus helps to sterilize the contact lenses.
U.S. Pat. No. 4,697,605 Yung uses the waste heat generated by the device described in the previous patent to heat the cleaning liquid in the cavity of the device.
U.S. Pat. No. 4,991,609 Browning, uses an ultrasonic and heating method for cleaning toothbrushes with filter means to allow separation of particulate matter followed by a 30-minute heat cycle at 65 degrees centigrade.
U.S. Pat. No. 5,129,410 Ifejika describes a rotating agitating device operating at a frequency of 10-100 Hz using electromagnetic reciprocating means to produce high energy vibrations to shake lenses clean in a rotational or linear method.
U.S. Pat. No. 6,183,705 Ching-Tsiai Chang, describes suspending contact lenses in a cleaning cup that fits into a chamber that provides ultrasonic and heating means and has a 20-30 minute cleaning cycle. The contact lenses are covered with a grille that allows the substance adhering to the lenses to be removed and to settle to the bottom of the cleaning medium. The heating means follow the ultrasonic cleaning means.
U.S. Pat. No. 6,193,806 Reed, uses a torsion spring that causes high amplitude vibrations to dislodge contaminants of the surface of the lenses.
There are several patents in the prior art that describe the use of ultrasonics as a cleaning method for metals and other hard surface materials. Ultrasonics has also been described in the literature as a method of cleaning hard plastics. It has been described as effective for metals, glass, ceramic and dense plastics and ineffective for soft materials like rubber, Styrofoam, and soft stones like pearls and opals. In directions for operating jewelry sonicators, consumers are specifically advised not to put soft stones like pearls in the cleaners that operate at 20 watts or higher power because of cracking and discoloration that can happen.
This method of cleaning contact lenses using ultrasonic waves, is distinguished from prior art because it is simple, works well with water and only requires a small amount of sterile saline or a small amount of contact lens solution. This method takes only a few minutes of time and is economical after the initial purchase of the ultrasonic device. This method can accommodate all varieties of store bought standard nonporous contact lens containers. When the Bradford protein analysis, a dye technique to determine protein deposits, is tested with this method, the contact lenses remain protein free. Additionally, this method helps to keep the contact lens storage container clean. This method is suited for people who develop allergic reactions to chemicals found in over the counter contact lens cleaning and disinfecting solutions and wetting drops. This method is successful without relying on a subsequent heating cycle. This method is successful with ‘soft’ lenses because the lenses are protected during the ultrasonic process, by floating in a cushion of liquid within their liquid impermeable lens container.